1. Field of the Invention
The present invention relates to a liquid crystal display.
2. Description of the Related Art
A liquid crystal display (LCD), a plasma display panel (PDP), a flat emission display (FED), a vacuum fluorescent display (VFD), and an organic light emitting device (OLED) are among widely used flat panel displays. An LCD includes two panels provided with field-generating electrodes such as pixel electrodes and a common electrode, and a liquid crystal (LC) layer interposed therebetween. The LCD displays images by applying voltages to the field-generating electrodes to generate an electric field in the LC layer which determines orientations of LC molecules in the LC layer and adjusts the polarization of incident light.
The LCD has a characteristic that viewing angle and contrast ratio change with the viewing angle, maximum luminance being displayed at a position that is perpendicular to the surface of the screen and is gradually reduced as the viewing angle increases. A reference viewing angle is defined as the viewing angle that makes the contrast ratio equal to a reference value. It is preferable that a wide reference viewing angle be obtained so as to permit viewing of normal images at a wider angle.
Particularly, when simultaneously displaying images to many viewers, normal images having a contrast ratio equal to or greater than the reference value must be displayed from the side angle as well as from the front. For these reasons.
However, for inputting personal information in a public environment, drafting or perusing secret documents, or executing preservation work, LCDs having a narrow viewing angle must be provided, as well as those with a wide viewing angle.